Hydraulic derrick assembly



Nov. 1, 1966 v .1. R. BUNN 3,

HYDRAULIC DERRICK ASSEMBLY 4 Sheets-Sheet 1 Filed May 12, 1965 (John F. Eon/7 INVENTOR.

ATTQR/VEVJ Nov, 1, 1966 J. R. BUNN 3,282,357

HYDRAULIC DERRICK ASSEMBLY Filed May 12, 1965 4 Sheets-Sheet 2 do/Vn .50/7/7 INVENTOR.

.BYQMJOL/ 2 7 M ATTO/PA/EVJ Nov. 1, 1966 J. R. BUNN 3,282,357

HYDRAULIC DERRICK ASSEMBLY 1 l I I I 1/0/20 /5. Bun/7 .73 IN VENTOR.

BYfiMaM 6071M 36 35 ATTOR/VEVJ Patented Nov. 1, 1966 3,282,357 HYDRAULIC DERRICK ASSEMBLY John R. Bunn, 325 W. 4th St, Tyler, Tex. Filed May 12, 1965, Ser. No. 459,144 11 Claims. (Cl. 175-122) This is a continuation-in-part application of my cpending application entitled Hydraulic Derrick Assembly, application Serial No. 269,546, filed April 1, 1963, now abandoned.

This invention relates to drilling apparatus and more particularly to hydraulic derricks.

Basically oil field drilling operations have been conducted by use of drilling rigs employing draw Works, drilling line, crown block, and traveling block which together cooperate to form a block and tackle assembly for supporting and lifting drilling pipe and related equipment during drilling operations.

The conventional block and tackle equipment is heavy and to 'be conveniently accommodated, requires a big derrick and substructure as well as a large operating crew. The weight of a derrick and related equipment is important in that a heavy derrick is more expensive in many circumstances to move between drilling locations. With the present trend in many areas to drill deeper holes, the equipment necessary to support the longer strings of drill pipe is even heavier than previously used equipment and .because of its greater weight, is even more expensive to relocate.

To alleviate some of the weight problems incident to the use of block and tackle assemblies usually associated with conventional derricks, hydraulic derricks employing cylinder and ram assemblies to lift the string of drill pipe have been utilized.

However, presently used hydraulic derricks to support the weight of the long drill strings necessary for deep drilling are also relatively heavy in that the pistons which must be used to support the loads of the longer strings of drill pipe are large solid steel pistons having great Weight.

Accordingly, it is an object of this invention to provide a derrick which, while light, is structurally able to support the greater weight of drill strings of pipe used for deep drilling.

Yet another object of this invention is to provide improved means for selecting the mechanical advantage of a derrick.

Another object of this invention is -to provide a light weight derrick which increases in structural rigidity as greater loads are applied to the derrick.

Another object of the invention is to provide an improved derrick which has great structural rigidity but which is light of weight, and therefore easy to transport.

Still another object is to provide a derrick which is not only practical for the increased Weight incident to deep drilling operations, but is equally as practical and efiicient for shallow drilling operations.

The present invention, by employing a hydraulic derrick structure having a hollow ram member which is adapted for reception of a hydraulic fluid therein, provides a derrick which is light in weight and which has relatively great structural rigidity. A hollow ram member 'becomes relatively rigid upon the introduction of a pressurized hydraulic fluid into the hollow portion thereof, and the higher the pressure of the fluid, the greater is the rigidity of the ram.

Other objects of the invention will be apparent from the following description of that embodiment of the invention which is illustrated in the attached drawings.

In the drawings: FIG. 1 is a side elevation of a hydraulic derrick employing one embodiment of the invention and shown in partially extended position.

FIG. 2 is another side elevation showing the derrick of FIG. 1 in retracted position.

FIG. 3 is a side elevation view illustrating the hydraulic boom used in hoisting stands of pipe after disengagement of a stand from the drill string.

FIG. 4 is a top plan view taken along line 44 of FIG. 3

FIG. 5 is a section view taken along line 55 of FIG. 3.

FIG. 6A is an enlarged section taken along line 6A- 6A of FIG, 2, after rotating FIG. 2 ninety degrees.

FIG. 6B is an enlarged section taken along line 6B 6B of FIG. 2, after rotating FIG. 2 ninety degrees.

In the drawings, reference numerals have been employed to indicate parts as follows:

Cylinder Collar Substructure Main platform Fixed slips Drill string Outer ram Innerram Recess Not used Chamber Aperture Groove O-ring Elongate extension Plug Outer ram end Weld Aperture Not used Brass ring Valve Conduit Inner ram end Plug Aperture Ring Flange Weld Not used Flange Bolt O-ring Groove Bolts Flange Cylinder end Weld Flange Not used Bolt Coupling Bolt Annular ring Packing gland assembly Cap Packing ring Packing Outer ram end Not used Packing gland ring Cap Packing gland assembly (54) Annular ring (55) Packing (56) Inner ram end (57) Weld (5 8) Bolt (59) Horizontal brace (60) Not used (61) Nuts (62) Bolt end (63) Shoulder (64) Flange (65) Surface (66) Stops (67) Surface (68) Surface (69) Support member (70) Bolt (71) Nut (72) Weld (73) End (74) Traveling platform (75) Guides (76) Power swivel (77) Bearing (78) Piston (79) Runners (80) Not used (81) Traveling slip (82) Power tong (83) Brace (84) Pin (85) Boom (86) Rod (87) Hole (88) Cylinder (89) Piston (90) Not used (91) Pulley (92) Derrick platform (93) Pin (94) Extension (95) Platform (96) Brace (97) Brace (98) Brace (99) Hoist line (100) Not used (101) Elevator (102) Drum (103) Opening (104) Conduit (105) Joint (106) Joint 3 (107) Stand of pipe (113) Groove (108) Shoulder (114) Flange (109) Base (115) O-ring (110) Pin (116) Groove (111) Coupling (117) Swivel pin (112) O-ring (118) Skids Although specific terms are used in the following description for clarity, and to aid in the disclosure of one embodiment of the invention, they are not intended, nor should they be construed, to limit the scope or define the invention.

The embodiment of the invention illustrated in the drawings has four cylinders 1 spaced in a rectilinear arrangement such as illustrated in FIG. 4, which function as leg members and which are connected through a collar 2 to a four legged substructure 3 which is provided with couplings 111 for leveling the derrick. While the illustrated derrick utilizes four legs, it is obvious that a derrick may conveniently be constructed having a different number of legs. Secured to substructure 3 by any convenient means are skids 118 to facilitate movement of the derrick.

Secured to the collar 2 is the main platform 4 which supports the fixed slips 5, the function of which Wlll be explained later.

Slidably and coaxially disposed in each of the cylinders 1 is an outer telescoping ram member 7 which slidably and coaxially carries an inner ram member 8.

Collar 2, which connects cylinder 1 to substructure 3 as before explained, has a circular recess 9 provided 1n the top portion and a cylindrical chamber 11 provided in the bottom. The cylindrical aperture 12 connecting recess 9 and chamber 11 through the body of collar 2 is provided with circular grooves 13 adapted to carry O-rmgs 14. The O-rings 14 cooperate with elongate cylindrical extension 15 of cylindrical plug 16 to form a fluid seal between the outer surface of extension 15 and aperture 12. Plug 16 is secured in the lower end 17 of outer ram 7 by weld 18. Plug 16 has an aperture 19 extending therethrough to communicate the inner ram member 8 with chamber 11 provided in the bottom of collar 2. Plug 16 has a brass ring 21 secured about the portion of its perimetric surface to abuttably engage the wall of collar 2 and the inner wall of cylinder 1. Ring 21 is provided with indentions, not shown, at spaced intervals around the circumference to allow passage of a hydraulic fluid, such as oil, for lubricating ring 21 and the walls of collar 2 and cylinder 1.

The recess 9 and chamber 11 in collar 2 are connected through valve 22 by conduit 23.

Inner ram 8 is carried within outer ram 7 and has secured to the lower end 24 a plug 25 which is provided with an aperture 26. Secured about plug 25 is a bronze ring 27 which abuttably engages the inner wall of outer ram 7 and which similar to plug 16, has indentions around its circumference to allow hydraulic fluid passage for lubrication of ring 21 and the inner wall of outer ram 7.

Securing cylinder 1 to collar 2 is a flange 28 which has been welded to cylinder 1 by circular weld 29, the flange 28 being secured to the cooperating flange portion 31 of collar 2 by means such as bolts 32. The connection between flanges 28 and 31 is secured from leakage by O-ring 33 disposed in groove 34 of flange 28.

The bottom of collar 2 is secured to the substructure 3 by bolts 35 passing through the bottom flange portion 36 of collar 2.

Cylinder 1 has the upper end 37 secured by weld 38 to flange 39. Flange 39 is secured as by bolts 41 to coupling 42, the bottom portion of which is best illustrated in FIG. 6B and the top portion of which is best illustrated in FIG. 6A. The fluid seal between flange 39 and coupling 42 is maintained by O-ring 112 disposed in circular groove 113.

Turning now to FIG. 6A, coupling 42 is secured by bolt 43 to a flange portion 114 of the externally threaded annular ring 44 which forms part of packing gland assembly 45. The connection is maintained fluid tight by O-ring disposed in circular groove 116. The threaded portion of annular ring 44'is matably received by cap 46 which through annular packing rings 47 compress packing 48 against the inner surface of threaded flange 44 and the outer surface of outer ram member 7 to create a fluid seal. The bottom of coupling 42 and bolt 43 will abuttably engage the top of guides 75 secured to platform 74 when either the inner ram 8 or the outer ram 7 is fully extended to prevent rams 7 or 8 from blowing-out of cylinder 1.

The upper end of ram 7 is threaded to engage a packing gland annular ring 51 which in turn threadably engages cap 52 of packing gland assembly 53. Cap 52 through annular metal rings 54 compresses a packing 55 against the outer surface of inner ram 8 and the inner surface of gland ring 51 to create a fluid seal.

Secured to the upper end 56 of inner ram 8 by weld 57 is bolt 58. Bolt 58 clamps the horizontal brace 59 between the nuts 61 secured to the threaded end 62 and the shoulder 63. Horizontal brace 59 supports the load placed on the derrick as will later become apparent.

A brief explanation of the operation of the telescoping ram members 7 and 8 will aid in a later discussion of the other equipment.

If it is desired to operate only the inner telescoping ram member 8, the valve 22 communicating recess 9 and chamber 11 in collar 2 through conduit 23 is closed and a hydraulic fluid, which may conveniently be oil, is introduced under pressure into'chamber 11 through conduit 1114 from a convention fluid pump not shown. The fluid then communicates through the aperture 19 in plug 16 to the inner ram 8. The fluid travels up through the inside of the ram member 8 and around the indentions in ring 27 to fill the space defined between the outer wall of ram 8 and the inner wall of ram 7. The hydraulic fluid pressure acting on the bottom surface 65 of bolt 58 urges the inner ram 8 and horizontal brace 59 in a vertical direction.

If both ram members 7 and 8 are to be utilized, valve 22 is opened to allow fluid flow between recess 9 and chamber 11. Fluid then flows around the upstanding cylindrical stops 66 spaced about the bottom of recess 9. Because the surface area of outer ram 7 against which the fluid can exert an upward force is greater than is the area presented by the inner ram 8, the outside ram 7 is urged in a vertical direction causing cap 52 illustrated in FIG. 6A to abut horizontal brace 59 and displace both the horizontal brace 59 and the inner ram 8 which, as explained before, is attached to horizontal brace 59.

When the two telescoping ram members 7 and 8 are completely collapsed, outer ram 7 will rest on stops 66 and the inner ram 8 which is shown in FIG. 6B in a partially extended position will collapse so that horizontal brace 59 abuts the top of cap 52, and the load carried by the horizontal brace 59 will be carried through cap 52 by the outer ram 7.

Depending from horizontal brace 59 is a cylindrical support member 69 which is secured to the horizontal brace 59 by bolt 70, nuts 71, and weld 72.

The four support members 69 are secured at the top to horizontal brace 59 as before explained and are similarly fixed at the other end 73 to a traveling platform 74 WhlCh is guided in its vertical movement by guides 75 secured to platform 74 in any conventional manner. Secured to the top of platform 74 is a hydraulically operated power swivel 76 of a conventional type which is illustrated in FIG. 5. The power swivel 76 is pivotal in a plane vertical to the plane of platform 74 through bearings 77 and also movable in the horizontal direction by pistons 78, which when actuated, removes swivel 76 along runners 79 secured to platform 74, for example, see FIG. 3, which illustrates the power swivel 76 in its off-center position.

Also secured to support members 69 and movable therewith are hydraulically operated traveling slips 81 of a conventional design. Mounted on cylinder member 1 by a mounting not shown are hydraulically operated power tongs 82 of a conventional design.

Secured to the bottom of substructure 3 is a brace member 83 which is connected by pin 84 to a telescoping boom 85, the height of which can be adjusted by aligning a hole provided in rod 86 with one of the holes 87 provided in base 109 .and extending a pin through the registering holes.

At the top of boom 85 is a hydraulic cylinder 88 and its cooperating piston 89, the end of piston 89 being forked to receive a pulley 91 which is rotatable about a pin 110 secured through the pulley 91 and the piston 89.

The telescoping boom 85 is secured in the vertical direction by attachment to a derrick platform 92 which in turn is secured by pin 93 to an extension 94 welded to coupling 42. Platform 95 similar in appearance to horizontal brace 59 illustrated in FIG. 4, is secured between couplings 42 to further rigidify the derrick and derrick platform 92. To provide additional support for the hydraulic cylinder 88 and piston 89, support braces 96, 97, and 98 are provided, support braces 97 and 98 securing the cylinder 88 to extension 86 and support brace 96 securing the cylinder 88 to derrick platform 92.

. Hoist line 99 carried by pulley 91 has .an elevator 101 of a conventional design attached to one end; the other end being disposed around a drum 102 which is driven by any suitable power means, not shown.

To commence drilling operations, the inner ram 8 and the outer ram 7 are collapsed .and the power swivel is rotated about bearings 77 to align the pin end 117 of the swivel with the box end of a pipe having a drill bit attached to the opposite end. The power swivel 76 is reversible in that the pin end 117 of the swivel can be rotated in either direction depending upon the choice of hydraulic fluid flow through the swivel 76 chosen by the operator. After the pin end 117 of swivel 76 and the box end of the pipe are aligned as described above, the swivel pin 117 is rotated in a direction desired to engage it with the box end of the pipe and rotation is stopped when the connection has been made. Then, either the inner ram 8 or both the inner ram 8 and the outer ram 7 are actuated by introducing hydraulic fluid into chamber 11 through conduit 104 from a pump not shown, the choice of rams depending upon the speed of extension desired.

For simplification of explanation, it will be assumed that valve 22 is closed and the inner ram 8 is the one actuated. As inner ram 8 extends from cylinder 1, the horizontal brace 59 through support members 69 and platform 74 picks up the power swivel 76, pipe, and bit. When the pipe and bit reach a vertical position the bit and pipe are lowered through the open jaws of the fixed slips until the bit contacts the earth. In case a large bit is used and the jaws of thte fixed slip 5 will not accommodate the passage of the bit through the jaws, the same drilling procedure described above will be followed, except the bit will have to be attached to the drill pipe after the pipe has been slipped through the jaws of the fixed slips 5. In either case once the drill bit has contacted the earth, the swivel 76 is actuated to commence rotation and thereby drilling. Hydraulic fluid pressure is then released from the ram 8 and the Weight of the supports 69, swivel 76, and other equipment depending from the horizontal brace will provide the pressure necessary to force the drill bit downward. If the entire weight of the depending equipment is in excess of that desired, controlled release of hydraulic pressure on the ram 8 can supply the amount of force desired.

When the drilling has proceeded to a depth where the derrick is collapsed, the fixed slips 5 are then hydraulically set to lock the pipe in position and prevent the rotation of the drill pipe which now is called the drill string 6. The swivel 76 is then actuated in a reverse direction to that used to make up the pipe joints in order that the pin 117 of the swivel may be disengaged from the drill string 6 held by the fixed slips 5. The swivel is rotated about bearings 77 and another joint of pipe is made up with the swivel pin 117 as explained before, the inner ram 8 actuated and the pipe joint lifted vertically until the pin end of the pipe is aligned with the box end of the drill string 6 held by the fixed slips 5. The inner ram 8 is then lowered until the joints contact at which time the swivel 76 is actuated to make up the joint, the fixed slips 5 are released, and the drilling commenced.

To remove the string of pipe 6 from the hole, the drill- 1 ing is ceased, the fixed slips 5 are engaged with the pipe, swivel 76 is actuated in direction necessary to disengage the connection with the swivel pin 117 and the drill string box. When the joints are disengaged, the pistons 78 move the power swivel 76 off center as illustrated in FIG. 3. Y

The fluid pressure on ram 8 is released and the traveling slips 81 lowered until the jaws of the slips 81 are below the box end of the upstanding joint of drill string 6 held by fixed slips 5. The traveling slips 81 are then actuated causing the jaws of traveling slips 8-1 to engage the upstanding joint of the drill string 6. The fixed slips 5 are then disengaged and the inner ram 8 actuated to lift the drill string 6 from the hole. With a derrick having an extension only great enough to remove one joint of the drill string 6 in one extension, it is nevertheless possible with the structure shown in FIG. 3 to remove a double joint of the drill string. It is accomplished thusly; after the one joint of the drill string 6 has been removed from the hole, as explained above, the fixed slips 5 are set, the traveling slips 81 released, and the ram 8 protracted or collapsed. The fixed slips 81 are then engaged, below the box end of the second joint which now extends above the fixed slips 5, the fixed slips 5 released and the inner ram 8 is actuated to lift an additional joint of the drill string 6 from the hole, and as the first joint of pipe 105 extends above the power tongs 82 as illustrated in FIG. 3, fixed slips 5 are set, the traveling slips 81 are released, and after the hydraulic piston 89 of boom extends and elevator 101 is lowered through the opening 103 in horizontal brace 59, illustrated in FIG. 4 and placed about the top end of the drill string 6 as shown in FIG. 3, the power tongs 82 are actuated. The jaws of the power tongs 82 rotate in a direction necessary to break and threadably disengage joint 106 from drill string 6. The power tongs 82 are then disengaged, drum 102 is actuated to lift elevator 101 and drill pipe joints 105 and 106 which are disengaged from the drill string 6. Piston 89 is retracted, and the stand of pipe 107 stacked on the derrick platform 92. When the stand of pipe connecting joints 105 and 106 is to be placed back into the hole, the procedure is reversed.

While the above operating procedures have been explained with only the inner ram 8 being actuated, it is obvious that valve 22 could have been opened and the outer ram 7 used just as easily. One of the significant advantages to having the two rams 7 and 8 is that with a given hydraulic pump having a maximum pressure discharge, the operator of the derrick can choose between inner ram 8 and outer ram 7, depending upon the mechanical advantage necessary to give him either the speed desired, or the lifting force desired.

The hydraulic lines furnishing power for power tongs 82, power swivel 76, traveling slips 81, fixed slips 5, and cylinder 88 and piston 89, have not been shown as they are not part of the invention and because the equipment necessary is of a conventional type, and for the same reason the drilling fluid line is not shown connected to the power swivel, although in actual practice there is such a line available for use.

While the embodiment of the invention illustrated and described utilizes inner and outer telescoping ram members it is evident that a single hollow ram member having such as inner ram 8 can be used to fabricate a lightweight derrick with relatively great rigidity, and indeed such a derrick structure would be one embodiment of the invention.

It is also apparent that one embodiment of the invention could be a structure wherein the hollow ram is filled with a pressurized hydraulic fluid, sealed at the open end, and utilized as a conventional hydraulic ram. This would both reduce the weight of the derrick as well as provide a hydraulic ram with relatively great rigidity.

Such a structure would indeed be another embodimen of the invention.

It is further apparent that any hydraulic fluid may be used to actuate the ram or rams such as oil, water, air, or other suitable hydraulic fluid.

Because the appurtenant equipment used in connection with the hydraulic derrick can be hydraulically actuated, few personnel are required to operate the equipment.

Also because of the light weight of the derrick due to decreased weight of the hydraulic rams and the elimination of heavy block and tackle equipment, the derrick can be easily transported without comparatively great expense.

I claim:

1. A hydraulic actuator for raising drill string in a drilling derrick, comprising a collar including a chamber of hydraulic fluid to which external actuating pressure is applied,

said first end of said collar having an outwardly opening aperture connecting to said chamber;

a cylinder secured to said first end of said collar, thereby providing a transverse surface on said first end of said collar between said aperture and said cylinder;

a first hollow ram coaxially carried within said cylinder;

an elongate plug secured to the end of said first ram located nearest said collar and provided with an aperture therethrough to the hollow of said first ram,

said plug having a diameter less than the diameter of said first ram, thereby providing a transverse actuating shoulder on said first ram between the periphery of said first ram and the periphery of said plug, said elongate plug being adapted for matable engagement with and movement within said aperture provided in said first end of said collar; at least one spacing stop located between said trans verse shoulder on said first ram and said transverse surface on said first end of said collar to define an opening therebetween for permitting the receiving of fluid;

a second hollow cooperating ram coaxially carried within said first ram and having a transverse actuating shoulder different in area from the transverse shoulder on said first ram,

said second ram being actuated by hydraulic fluid being forced from said chamber in said collar and passing through said aperture in said elongate plug;

a passage from said chamber to said opening between said transverse shoulder on said first ram and said transverse surface on said first end of said collar; and

means for selectively directing the force of the hydraulic fluid from said chamber to said transverse actuating shoulder of said first ram for multi-speed extension and structural rigidity of the hydraulic actuator.

2. A hydraulic actuator suitable for raising drill string in a drilling derrick, comprising a cylinder;

an outer ram coaxially carried within and movable relative to and at least partially extendable from one end of said cylinder,

said outer ram having an imperforate side wall and a hydraulic actuating surface area transverse to said side wall, the outer surface of said wall of said outer ram being spaced from the inner surface of said cylinder to define a first fluid-receiving annulus therebetween; first seal means enclosing said first fluid-receiving annulus at the end of said cylinder from which said outer ram moves;

an inner ram coaxially carried within said outer ram and movable relative to and at least partially extendable from the same end of said cylinder as said outer ram,

said inner ram having an imperforate side wall and a hydraulic actuating surface area different from the hydraulic surface area of said outer ram,

the outer surface of the side wall of said inner ram being spaced from the inner surface of the side wall of said outer ram to define a second fluidreceiving annulus therebetween;

second seal means enclosing said second fluid-receiving annulus at the end of said cylinder from which said inner ram moves;

a source of pressure including a chamber;

a first passage communicating said chamber with said hydraulic actuating surface area of said inner ram;

a second passage communicating said chamber with the hydraulic actuating surface area of said outer ram; and

a valve in said second passage to selectively control fluid flow therethrough;

a fluid freely flowing from said chamber through said first passage against said hydraulic actuating surface area of said inner ram and into the annulus between said inner and outer rams;

fluid freely flowing from said chamber through said second passage upon opening of said valve against said hydraulic actuating surface area of said outer ram and into said annulus between said outer ram and said cylinder;

whereby fluid flowing through said first passage completely fills the fluid-receiving annulus between said inner and outer rams to enhance the column strength of said rams, and fluid flowing through said second passage as controlled by said valve completely fills the fluid-receiving annulus between said cylinder and said outer ram to enhance the column strength of said cylinder and said outer ram,

said fluid flowing into the respective fluid-receiving annuluses only from adjacent the hydraulic actuating surface areas of the respective rams.

3. A hydraulic actuator in accordance with claim 2, wherein the actuating surface area of said outer ram is greater than the actuating surface area of said inner ram.

4. A drilling derrick, comprising as one of the supporting legs a cylinder;

an outer ram coaXially carried Within and movable relative to and at least partially extendable from one end of said cylinder,

said outer ram having a hydraulic actuating surface area transverse to the direction of movement of said outer ram;

an inner ram coaxially carried within said outer ram and movable relative to and at least partially extendable from one end of said cylinder,

said inner ram having a hydraulic actuating surface area transverse to the direction of movement of said inner ram different from the hydraulic surface area of said outer ram;

a source of pressure including a chamber, said chamber in communications with the hydraulic actuating surface area of said inner ram;

a passage communicating said chamber with the hydraulic actuating surface area of said outer ram; and

a valve for selectively controlling the fiow of fluid from said chamber to the hydraulic actuating surface area of said outer ram.

5. A drilling derrick in accordance with claim 4, wherein the actuating surface area of said outer ram is greater than the actuating surface area of said inner ram.

6. A drilling derrick, comprising as one of the supporting legs a cylinder;

a collar secured to one end of said cylinder,

said collar including a chamber in communication with a source of hydraulic pressure;

an outer ram coaxially carried within and movable relative to and at least partially extendable from on'e end of said cylinder,

said outer ram having a hydraulic actuating surface area transverse to the direction of movement of said outer r-am;

an inner ram coaxially carried within said outer ram and movable relative to and at least partially extendable from one end of said cylinder,

said inner ram having a hydraulic actuating surface area transverse to the direction of movem'ent of said inner ram different from the hydraulic surface area of said outer ram;

said chamber in communications with the hydraulic actuating surface area of said inner ram;

a passage communicating said chamber with the hydraulic actuating surface area of said outer ram; and

a valve for selectively controlling the flow of fluid from said chamber to the hydraulic actuating surface area of said outer ram.

7. A drilling derrick, comprising as one of the supporting legs a cylinder;

an outer 11am coaxially carried within and movable relative to and at least partially extendable fnom one end of said cylinder,

said outer ram having a hydraulic actuating surface area transverse to the direction of movement of said outer ram;

an inner ram coaxially carried within said outer ram and movable relative to and at least partially extendble from one end of said cylinder,

said inner ram having a hydraulic actuating surface area transverse to the direction of movement of said inner ram different from the hydraulic surface area of said outer ram;

a source of pressure including a chamber, said chamber in communications with the hydraulic actuating surface area of said inner ram;

a passage communicating said chamber with the hydraulic actuating surface area of said outer ram;

a valve for selectively controlling the flow of fluid from said chamber to the hydraulic actuating surface .area of said outer ram;

stop means secured to the outside surface of said cylinder;

a movable derrick member secured to the extendable end of said inner nam for movement therewith,

said movable derrick member being also movable by the extendable end of said outer ram upon actuation thereof;

load-carrying means attached to said movable derrick member for movement therewith;

said movable derrick member including limit means for contacting said stop means to limit the movement of said movable derrick member.

8. A drilling derrick, comprising as one of the supporting legs a cylinder; an outer ram coaxially carried Within and movable relative to and at least partially extendable from one end of said cylinder,

said outer ram having a hydraulic actuating surface area transverse to the direction of movement of said outer ram;

an inner ram ooaxially carried within said outer ram and movable relative to and at least partially extend-able from one end of said cylinder,

said inner ram having a hydraulic actuating surface area transverse to the direction of movement of said inner ram different from the hydraulic surface area of said outer ram;

a source of pressure including a chamber, said chamher in communications with the hydraulic actuating surface area of said inner ram;

a passage communicating said chamber with the hydraulic actuating surface area of said outer ram;

a valve for selectively controlling the flow of fluid from said chamber to the hydraulic actuating surface area of said outer ram;

stop means secured to the outside surface of said cylinder;

a horizontal movable brace secured to the extendable end of said inner ram for movement therewith,

said movable brace being also movable by the extendable end of said outer ram upon actuation thereof;

a support secured to said movable brace extending xalongside said cylinder;

at load-carrying platform secured to said support at a position remote from said support, said platform including guide means for riding the outer surface of said cylinder, said guide means contacting said stop means to limit the movement of said loadcarrying platform.

9. A drilling derrick in accordance with claim 8, and

including a power swivel attached to said platform positionable for handling drilling pipe;

travelling slips secured to said support for movement therewith and aligned with said power swivel; and

power tongs secured to said cylinder and positionable for alignment with said power swivel for handling drilling pipe.

10. A drilling derrick, a portion of which is fixed, comprising as one of the supporting legs a cylinder;

an outer rarn coaXially carried within and movable relative to and at least partially extendable from one end of said cylinder,

said outer ram having a hydraulic actuating surface area transverse to the direction of movement of said outer nam;

an inner hollow ram co-axially carried within said outer ram and movable relative to and at least partially extendable from one end of said cylinder,

said inner nam having a hydraulic actuating surface area transverse to the direction of movement of said inner ram different from the hydraulic surface area of said outer ram;

a source of pressure including a chamber, said chamher in communications with the hydraulic actuating surface area of said inner ram;

a passage communicating said chamber with the hydraulic actuating surface area of said outer 11am; valving means for selectively controlling the flow of fluid in said passage from said chamber to the hydraulic actuating surface area of said outer ram;

a movable derrick member secured to the extendaole end of said, inner ram for movement therewith,

said movable derrick member being also movable by the extendable end of said outer ram upon actuation thereof;

load-carrying means attached to said movable derrick member for movement therewith; and

means carried by said movable derrick member for engaging a fixed structure of the derrick upon move- 1 l ment of said movable derrick member to its extended position.

11. A hydraulic actuator suitable for raising drill string in a drilling derrick, a portion of which is fixed, comprising a cylinder;

an outer ram colax-ia lly carried Within and movable relative to and at least partially extendable from one end of said cylinder,

said outer ram having an imperforate side wall and a hydraulic actuating surface area transverse to said side wall, the outer surface of said side wall of said outer ram being spaced from the inner surface of said cylinder to define a first fluid-receiving annulus therebetween; first seal means enclosing said first fluid-receiving annulus at the end of said cyilinder from which said outer ram moves;

an inner ram coaxially carried within said outer ram and movable relative to and at least partially extendable from the same end of said cylinder as said outer ram,

said inner ram having .an imperforate side wall and a hydraulic actuating surface .area different from the hydraulic surface area of said outer ram, the outer surface of the side wall of said inner ram being spaced from the inner surface of the side wall of said outer 11am to define a second fluid-receiving annulus therebetween; second seal means enclosing said second fluid-receiving annulus at the end of said cylinder from which said inner ram moves;

a source of pressure including a chamber;

a first passage communicating said chamber with said hydraulic actuating surface area of said inner ram;

a second passage communicating said chamber with the hydraulic actuating surface area of said outer ram;

a valve in said second passage to selectively control fluid freely flowing from said chamber through said first passage against said hydraulic actuating surface area of said inner ram and into the annulus between said inner and outer rams; fluid freely flowing from said chamber through said second passage upon opening of said valve against said hydraulic actuating surface area of said outer ram and into said annulus between said outer ram and said cylinder; whereby fluid flowing through said first passage completely fills the fluid-receiving annulus between said inner and outer rams to enhance the column strength of said ram-s, and fluid flowing through said second passage as controlled by said valve completely fills the fluid-receiving annulus between said cylinder and said outer ram to enhance the column strength of said cylinder and said outer ram,

said fluid flowing into the respective fluid-receiving annuluses only from adjacent the hydrauilc actuating surface are-as of the respective rams;

a movable derrick member secured to the extendable end of said inner ram for movement therewith,

said movable derrick member being also movable by the extendable end of said outer ram up on actuation thereof;

load-carrying means for raising drill string attached to said movable derrick member for movement therewith; and

means carried by said movable derrick member for engaging a fixed structure of the derrick upon movement of said movable derrick member to its extended position.

References Cited by the Examiner UNITED STATES PATENTS 2,179,557 11/1939 Mason 25430 2,334,312 11/1943 Oaldwell 173164 2,502,895 4/1950 Shaffer 91167 2,813,515 11/1957 Curtis 17336 3,128,674 4/1964 Ganchar et 'al. 91-167 3,158,213 11/1964 ONeill et a1. 17585 CHARLES E. OCONNELL, Primary Examiner.

J. A. LEPPINK, Assistant Examiner. 

4. A DRILLING DERRICK, COMPRISING AS ONE OF THE SUPPORTING LEGS A CYLINDER; AN OUTER RAM COAXIALLY CARRIED WITHIN AND MOVABLE RELATIVE TO AND AT LEAST PARTIALLY EXTENDABLE FORM ONE END OF SAID CYLINDER, SAID OUTER RAM HAVING A HYDRAULIC ACTUATING SURFACE AREA TRANSVERSE TO THE DIRECTION OF MOVEMENT OF SAID OUTER RAM; AN INNER RAM COAXIALLY CARRIED WITHIN SAID OUTER RAM AND MOVABLE RELATIVE TO AND AT LEAST PARTIALLY EXTENDABLE FROM ONE END OF SAID CYLINDER, SAID INNER RAM HAVING A HYDRAULIC ACTUATING SURFACE AREA TRANSVERSE TO THE DIRECTION OF MOVEMEMT OF SAID INNER RAM DIFFERENT FROM THE HYDRAULIC SURFACE AREA OF SAID OUTE RAM; A SOURCE OF PRESSURE INCLUDING A CHAMBER, SAID CHAMBER IN COMMUNICATIONS WITH THE HYDRUALIC ACTUATING SURFACE AREA OF SAID INNER RAM; A PASSAGE COMMUNICATING SAID CHAMBER WITH THE HYDRAULIC ACTUATING SURFACE AREA OF SAID OUTER RAM; AND A VALVE FOR SELECTIVELY CONTROLLING THE FLOW OF FLUID FROM SAID CHAMBER TO THE HYDRAULIC ACTUATING SURFACE AREA OF SAID OUTER RAM. 